wxml
<form bindsubmit='commentSubmit'><view class='text_box'><textarea fixed='true' contenteditable="true" contenteditable="true" auto-height="true" class='weui-textarea' name='commentValue' placeholder='评论' placeholder-style='font-size:30rpx;' maxlength='50' style='background-color: white'></textarea></view><button form-type='submit' class='textarea_btn'>发送</button></form>
wxss
/* pages/textareaAutoheight/textareaAutoheight.wxss */.text_box {background-color: white;width: 544rpx;border-radius: 10rpx;border: 1px solid #e9e9e9;padding-left: 28rpx;font-size: 30rpx;padding-top: 8rpx;}.text_box .weui-textarea {width: 528rpx;padding-left: 32rpx;padding: 6rpx 0;border-radius: 12rpx;}.textarea_btn {width: 96rpx;height: 60rpx;font-size: 30rpx;padding: 0;line-height: 60rpx;background-color: #f7ab21;color: white;}
